The LNCS journal Transactions on Computational Systems Biology is devoted to inter- and multidisciplinary research in the fields of computer science and life sciences and supports a paradigmatic shift in the techniques from computer and information science to cope with the new challenges arising from the systems oriented point of view of biological phenomena.

This volume, the 7th in the Transactions on Computational Systems Biology series, contains a fully-refereed and carefully selected set of papers from the two workshops BioConcur 2004 held in London, UK in August 2004 and BioConcur 2005 held in San Francisco, CA, USA in August 2005.

The 8 papers selected for this special issue are devoted to various aspects of computational methods, algorithms and techniques in bioinformatics such as modeling of signalling pathways, gene regulation in pi-calculus, relations between regulator graphs and Petri nets, translation of SBML models to stochastic pi-calculus, use of graph theory to model biological networks, distributed model checking with biochemical Kripke structures, graphical notation for stochastic pi-calculus, as well as differentiation and homeostatic behavior of boolean dynamic systems.